Initiation of PCSK9 inhibition in patients with heterozygous familial hypercholesterolaemia entering adulthood: a new design for living with a high-risk condition?

Aggregation Susceptibility of Low-Density Lipoproteins-A Novel Modifiable Biomarker of Cardiovascular Risk

Circulating low-density lipoprotein (LDL) particles enter the arterial intima where they bind to the extracellular matrix and become modified by lipases, proteases, and oxidizing enzymes and agents. The modified LDL particles aggregate and fuse into larger matrix-bound lipid droplets and, upon generation of unesterified cholesterol, cholesterol crystals are also formed. Uptake of the aggregated/fused particles and cholesterol crystals by macrophages and smooth muscle cells induces their inflammatory activation and conversion into foam cells. In this review, we summarize the causes and consequences of LDL aggregation and describe the development and applications of an assay capable of determining the susceptibility of isolated LDL particles to aggregate when exposed to human recombinant sphingomyelinase enzyme ex vivo. Significant person-to-person differences in the aggregation susceptibility of LDL particles were observed, and such individual differences largely depended on particle lipid composition. The presence of aggregation-prone LDL in the circulation predicted future cardiovascular events in patients with atherosclerotic cardiovascular disease. We also discuss means capable of reducing LDL particles' aggregation susceptibility that could potentially inhibit LDL aggregation in the arterial wall. Whether reductions in LDL aggregation susceptibility are associated with attenuated atherogenesis and a reduced risk of atherosclerotic cardiovascular diseases remains to be studied.

Mutational Spectrum of LDLR and PCSK9 Genes Identified in Iranian Patients With Premature Coronary Artery Disease and Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a common, yet underdiagnosed, genetic disorder characterized by lifelong elevated low-density lipoprotein cholesterol levels, which can increase the risk of early-onset coronary artery disease (CAD). In the present study, we screened the nucleotide variations of the LDLR and PCSK9 genes, as well as a part of the APOB gene, in Iranian patients with FH and premature CAD to find the genetic cause of the disorder. Fifteen unrelated individuals with a clinical diagnosis of FH and premature CAD were recruited. Direct DNA sequencing was applied to screen the whole coding exons and exon-intron boundaries of the LDLR and PCSK9 genes and the main parts of their introns, together with exon 26 of the APOB gene. The pathogenicity of the identified mutations was investigated via either segregation analyses in the family or in silico predictive software. Six different point mutations (p.Cys148Tyr, p.Cys216Tyr, p.Cys302Trp, p.Cys338Trp, p.Leu479Gln, and p.G593Afs∗72) in LDLR and a double mutation (p.Asp172His and p.Ala53Val) in both LDLR and PCSK9 genes were identified in seven families with clinically diagnosed FH (43%), whereas no pathogenic mutations were found in eight families with clinically diagnosed FH. This study is the first to identify 1 pathogenic mutation in the LDLR gene (c.1014C > G [p.Cys338Trp]) and to cosegregate it from the affected individual in the family. No mutations were found in the APOB gene, whereas several silent mutations/polymorphisms were identified in the LDLR and PCSK9 genes. Genetic testing and reports on nucleotide alterations in the Iranian population are still limited. Our findings not only further confirm the significant role of FH in the incidence of premature CAD but also enlarge the spectrum of LDLR and PCSK9 variations and exhibit the heterogeneity of FH in Iranians. In patients with no mutation in the examined genes, the disease could be begotten either by a polygenic cause or by gene defects occurring in other related genes and regions not targeted in this study.

Decreasing the Cholesterol Burden in Heterozygous Familial Hypercholesterolemia Children by Dietary Plant Stanol Esters

This review covers the current knowledge about plant stanol esters as a dietary treatment option for heterozygous familial hypercholesterolemia (he-FH) children. The current estimation of the prevalence of he-FH is about one out of 200–250 persons. In this autosomal dominant disease, the concentration of plasma low-density lipoprotein cholesterol (LDL-C) is strongly elevated since birth. Quantitative coronary angiography among he-FH patients has revealed that stenosing atherosclerotic plaques start to develop in he-FH males in their twenties and in he-FH females in their thirties, and that the magnitude of the plaque burden predicts future coronary events. The cumulative exposure of coronary arteries to the lifelong LDL-C elevation can be estimated by calculating the LDL-C burden (LDL-C level × years), and it can also be used to demonstrate the usefulness of dietary stanol ester treatment. Thus, when compared with untreated he-FH patients, the LDL-C burden of using statin from the age of 10 is 15% less, and if he-FH patients starts to use dietary stanol from six years onwards and a combination of statin and dietary stanol from 10 years onwards, the LDL-C burden is 21% less compared to non-treated he-FH patients. We consider dietary stanol treatment of he-FH children as a part of the LDL-C-lowering treatment package as safe and cost-effective, and particularly applicable for the family-centered care of the entire he-FH families.

Knowns and unknowns in the care of pediatric familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a common genetic disorder that causes elevated LDL cholesterol levels from birth. Untreated FH accelerates atherosclerosis and predisposes individuals to premature coronary artery disease (CAD) in adulthood. Mendelian randomization studies have demonstrated that LDL cholesterol has both a causal and cumulative effect on the risk of CAD. This supports clinical recommendations that children with FH commence pharmacological treatment from the age of 8 to 10 years, to reduce the burden of hypercholesterolemia. Worldwide, the majority of children with FH remain undiagnosed. Recent evidence suggests that the frequency of FH is at least 1 in 250 and this constitutes a public health issue. We review and identify the knowns and unknowns concerning the detection and management of pediatric FH that impact on the developing model of care for this condition.

Proprotein convertase subtilisin kexin type 9 inhibitors: update from clinical trials to real-world experience

PURPOSE OF REVIEW

After the approval of alirocumab and evolocumab, the first two monoclonal antibodies (mAbs) targeting proprotein convertase subtilisin kexin type 9 (PCSK9), this review provides an update on recent PCSK9 inhibitors data and describes recommendations for the use before the results of the ongoing cardiovascular endpoint trials.

RECENT FINDINGS

New studies and complementary analysis of phase III trials have consistently shown that alirocumab and evolocumab are highly effective in reducing LDL-cholesterol and to some extent lipoprotein (a). Some preliminary findings coming from exploratory and post-hoc analyses of the longer-term safety phase III trials and meta-analyses suggest that these mAbs can decrease the incidence of cardiovascular events. Whether or not mAbs targeting PCSK9 definitively reduce the incidence of cardiovascular events without safety concerns shall be demonstrated with the ongoing cardiovascular outcome trials. Waiting these outcome trials and given the high cost of these mAbs, groups of experts have proposed as priorities groups of patients with familial hypercholesterolemia and with atherosclerotic cardiovascular disease who have substantially elevated LDL-cholesterol on maximally tolerated statin/ezetimibe therapy.

SUMMARY

Before the results of large cardiovascular outcome trials, PCSK9 inhibitors should be only used in some categories of patients with familial hypercholesterolemia and/or with atherosclerotic cardiovascular disease.

Challenges in the health economics of familial hypercholesterolemia

PURPOSE OF REVIEW

Implementation of effective interventions often requires evidence regarding value, that is, whether they are worth what we pay for them. This review explores recent evidence concerning cost-effectiveness in familial hypercholesterolemia, and discusses the cause of, and likelihood of solutions to, the paucity of such evidence.

RECENT FINDINGS

Cost-effectiveness analysis in familial hypercholesterolemia has been limited almost exclusively to adult populations. However, there is growing evidence that childhood intervention offers substantial benefit in terms of downstream health gains. Statin therapy in adults has been demonstrated to be cost-effective, but the range of novel agents that might be used will require de novo economic evaluation alongside exploration of their effect and safety profile.

SUMMARY

The familial hypercholesterolemia field has limited evidence regarding cost-effectiveness, which limits optimum allocation of resources. Economic evaluations are necessary to appraise new agents and optimal timing of management approaches. Evaluations often have substantial data demands; consequentially, their applicability to medical decision-making or policy will be partly determined by the availability of data, particularly those providing information about the long-term trajectory of health benefit from familial hypercholesterolemia treatment.

Development of proprotein convertase subtilisin/kexin type 9 inhibitors and the clinical potential of monoclonal antibodies in the management of lipid disorders

The aim of this manuscript is to review available data to evaluate the present status of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors in the treatment of hypercholesterolemia. Relevant literature since 2003 is reviewed. The effectiveness of PCSK9 inhibitors in lowering low-density lipoprotein cholesterol and other atherogenic lipid fractions was studied in various Phase 2 and Phase 3 trials of Alirocumab, Evolocumab, and Bococizumab. The results of published long-term ODYSSEY and OSLER studies are summarized. There have been three excellent meta-analysis studies on PCSK9 inhibitors which are outlined. The complex problem of cost-effectiveness was carefully evaluated by the Institute for Clinical and Economic Review (ICER). The draft report (ICER-2015) is summarized herewith. The cardiovascular outcome trials with Evolocumab (FOURIER), Alirocumab (ODYSSEY OUTCOME) and Bococizumab (SPIRE-1 and SPIRE-2) are the ongoing clinical trials, and their results are expected in 2017-2018. The search for new cost-effective analogs of PCSK9 inhibitors is ongoing.